Project Summary Overview: Although magnetic resonance imaging (MRI) has shown clinical accuracy in detecting many types of breast cancer, higher-resolution MRI would potentially improve detectability of small lesions, diagnosis of ductal carcinoma in situ, and specificity of MRI for other cancers. Numerous recent advances in MRI technology will enable higher resolution exams, but have not yet been applied to fully optimize imaging for breast cancer. We propose to develop, implement and validate breast MRI methods with very high spatial-resolution at 3T. Significance: Although breast MRI has recently been shown to be cost-effective in screening high risk patients or patients with a contralateral breast cancer, its sensitivity to ductal carcinoma in situ, it's ability to assess small lesions, and its positive predictive value limit increased use. Higher resolution MRI could address all of these limitations, providing a more accurate tool for assessment of breast cancer. Improved specificity could reduce the rate of unnecessary biopsy while also making MRI effective for screening lower-risk patients. Increased sensitivity for small lesions could allow earlier detection of cancer resulting in increased survival rates and a reduced screening frequency. Approach: As a first aim, we will develop fat-suppressed ultra-high-resolution 3D MRI pulse sequences for T1-weighted and T2-weighted imaging at 3T, combining numerous advances in excitation pulse design, imaging and reconstruction. We will test the clinical utility of ultra-high-resolution imaging in a small patient study. Next, as a second aim, we will extend the high-resolution imaging methods for full bilateral breast coverage using high-density phased-array coils fitted specifically to the patient in order to provide maximal signal levels, volumetric coverage and parallel imaging capability. We will also apply software and hardware techniques to reduce sensitivity to magnetic field variations at 3T. The overall bilateral techniques will be tested in a second patient study to assess the utility of the complete high-resolution whole-breast imaging protocol. Project Narrative Magnetic resonance imaging (MRI) is an accurate method to detect breast cancer, and has recently been shown to be cost-effective in screening high-risk patients. This research will develop much higher resolution MRI, allowing it to better classify small lesions, prevent unnecessary biopsy, and detect cancer earlier.